After receiving a stem cell transplant, a 66-year-old man who infected with human immunodeficiency virus (HIV) in 1988 and battled with disease for more than three decades has been cured.
HIV destroys immune system cells in humans and, if untreated, can result in acquired immunodeficiency syndrome (AIDS), an incurable disease. Retroviral medications, which are now used to treat HIV, prevent the virus from replicating inside of cells. Nevertheless, the course of treatment is life long without medications virus counts can rise in the infected person.
Research centres all over the world are looking for cures that can keep infected people free of the virus without the need for daily drug administration. Chimeric antigen receptor (CAR) T cells are one of them; they have the ability to target only HIV-positive cells in the host, stopping the virus in its tracks. The second method involves eliminating the cells that the virus typically attacks in body.
A mutation that makes a world of difference
HIV targets the CCR5 receptor on a particular type of immune cell to gain entry into the immune system. But in certain people, a gene mutation known as delta 32 on the CCR5 protein gene leads to a receptor that is immune to an attack by HIV. The virus cannot replicate in the body without getting inside the immune system.
The benefit provided by this mutation has been utilised by researchers at the City of Hope cancer research facility in Los Angeles to treat HIV-positive patients. They can replace the recipient’s immune cells with ones that are resistant to HIV infection by receiving stem cells from a donor who carries the delta-32 mutation on the CCR5 gene.
Three other patients, one of whom was a woman, were treated with this procedure in the past. The oldest sufferer, however, is a recent case.
The not-so-straightforward transplant
Operating a stem cell transplant is a challenging surgery. According to a press release, in case of 66-year-old’s was made more difficult because he had developed acute myelogenous leukaemia (AML), a type of blood cancer that is frequently observed in persons who have lived long with HIV.
The patient underwent three chemotherapy treatments to put his cancer into remission before the transplant. The City of Hope team created a less aggressive chemotherapy regimen for transplant candidates who are older or less physically strong. His transplant took place three years ago, and he continued retroviral treatment until March 2021, when the research team said he could stop taking the drugs.
Since then, the patient has been under close observation for almost 17 months, but neither blood nor tissue samples have revealed any sign of the virus.
We now have evidence that if the right stem cell donor is found for patients living with HIV who develop blood cancers, we can use newer and less intensive chemotherapy regimen options to try to achieve a dual remission, according to Jana. K. Dickter, associate clinical professor at City of Hope. “This patient was the oldest to receive a stem cell transplant [of the four patients], has lived the longest with HIV prior to his transplant, and received the least immunosuppressive therapy,” she said. For elderly individuals with HIV and blood cancer, this could create whole new opportunities.